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Maximize Your Savings with Steam Trap Maintenance

December 13, 2010 - 2:23pm  Anonymous (not verified)

Steam traps are the heart of every steam heating system.The purpose of a steam trap is to prevent steam from passing beyond its point of use and to return the condensed steam (water) back to the boiler.The trap also vents the air.

If a trap fails open, live steam will be passed into the condensate return lines and many dollars of fuel will be lost.If a trap fails closed, water will flood the heating unit and cause havoc with the entire steam system.

Signs of trap failure:

• Overly warm boiler room

• Condensate receiver venting steam

• Condensate pump seal failing regularly

• Overheated or underheated areas

• Boiler pressure difficult to maintain

• Water hammer

• Steam in condensate lines

• High fuel bills

Try heating your house in the winter with the windows open.If you did this, your furnace or boiler would be running all the time, trying to keep up with the heat you’re losing.Steam traps are like windows on your heating equipment.The traps close to keep heat in.When a steam trap is stuck open, they can’t keep the steam in your heating units, and the boiler works overtime to produce steam you shouldn’t need!

How many actual dollars can a “bad” trap cost you?

For an example, lets use the smallest thermostatic radiator trap on a system with only five pounds operating pressure.This common trap is found on radiators/converters in most steam-heated buildings.These 1/2” I.P.S. traps have a 1/4” discharge orifice.At a steam pressure of 5 psig, the steam loss through a failed open trap is 31 lbs./hr.

A typical six-month heating season is from mid-October to mid-April, about 180 days.During this period, the boiler isn’t running 24 hours a day at 5-psig pressure (hopefully).If it was, 22,320 lbs. of steam would have been wasted!Realistically, about 25 percent of the steam is being lost over a six-month season.

Using an average cost of making steam of $8.00 per 1,000 lbs., we can figure out how much money a 1/2” I.P.S. failed thermostatic radiator trap wastes in six months.

31 lbs./hr x 24 = 744 lbs./day x 30 days = 22,320 lbs./mo.

22,320 lbs./mo. x 6 months = 133,920 lbs/6 mo.

133,920 x .25 = 33,480 lbs/6 mo.

33,480 ¸ 1,000 x $8.00 = $267.84!!

$267.84 Wasted per heating season for only one little trap!

Assume a building has 100 of these traps.Not unusual.Let’s also assume 20 of the traps aren’t working. Again, not unusual.20 x $267.84 = $5,356.80.That's $5,356.80 per heating season being totally wasted!

It costs about $40.00 for a whole new trap, repair elements are even less.It takes about 15 minutes to replace or repair a trap.Maintenance personnel can do the job during the non-heating season when the boiler is off.

If you invest $800.00 to replace or repair the defective traps, you’ll save $4,556.80 per heating season!

Steam trap maintenance should be the first priority of anyone with a steam heating system.The savings prove to be enormous.

When doing a steam trap survey, it is a good time to correct other problems.It is not at all unusual to find traps installed incorrectly and poor piping practices.

Look for traps installed upside down, or lying on their side.Especially F & T’s.Watch for high-pressure traps on low-pressure applications.Replace a wrong rated trap with the correct pressure rated trap.A high-pressure trap on a low-pressure system reduces the discharge capacity and can cause flooding of equipment.

Two heating units drained by a single trap is a common “money” saver done by uninformed installers.Two unit heaters fairly close together often get a “shared” trap.This is wrong.This will impede proper heat transfer.Each unit must have its own trap.See Figure 1.

Figure 1.

Avoid discharging condensate to overhead returns.Re-pipe if possible.If you must discharge to an overhead return, make sure you have enough steam pressure to get the condensate to the return.Steam pressure is what actually pushes the condensate out of the trap.1 psig of steam pressure will push condensate about 2 feet up.Always make sure there is a check valve installed after the trap when discharging to an overhead return.

When steam pressure or temperature regulator valves are installed in a steam line, condensate collects ahead of the valve when it is off.Then when the valve opens “water hammer” occurs.Slugs of condensate are slammed into the valve, shortening the life of the expensive valves.When the branch line from the steam main is less than 10 feet, you can pitch the branch line back towards the main to allow condensate to flow back into the main.If the branch is over 10 feet, pitch the branch line toward the regulating valve and install a steam trap at the inlet to the regulating valve.The “pitch” is 1/2 inch per foot.If in doubt, installing a trap is always correct, in fact, is best.See Figure 2.

Figure 2.

Many devices or systems have been marketed as trap testers.Devices such as stethoscopes, heat sensitive tapes, IR detectors to measure DT, etc. have all been used.All of those devices or systems take a high measure of expertise and a lot of experience with a particular steam system in order to diagnose failed traps.

Because defective traps are very expensive, consider installing a proven foolproof trap test system where F & T traps or bucket traps are used.These traps are usually found on higher capacity units than small radiator traps.Installing test valves on these larger traps will allow periodic testing during heating and can be done and correctly interpreted by almost anyone.The extra expense is easily justified.

See Figure 3.Install a full port ball valve (1), a strainer (2), and a union ahead of the trap.(A blow down assembly {3} is a good idea on the strainer).On the outlet side of the trap, install a union (4), a tee (5), another full port ball valve (6), and the full port “test” ball valve (7).Below the no. 7 test valve install a nipple and cap (8).With this testing assembly around the trap, you can test the trap performance “on line.”No more guessing if the trap works.The unit must be active.

Figure 3.

To test the trap:

Remove cap 8, shut off valve 6, open valve 7.Catch the discharge from 7 in a bucket.

A good trap will discharge small amounts of condensate with some steam vapors (the steam vapors are being generated by hot condensate being discharged to the atmosphere).A bad trap will discharge a steady pressure of steam, with small drops of water.If nothing comes out, the trap failed closed.

In the next Info-Tec (44), we will “troubleshoot” some common problems with steam systems, especially after someone has “repaired” something in the system.